// Copyright 2018 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. union DummyUnion { u8: u8, bool: bool, } #[repr(C)] #[derive(Copy, Clone)] enum Enum { A, B, C, } #[derive(Copy, Clone)] union Foo { a: bool, b: Enum, } union Bar { foo: Foo, u8: u8, } // the value is not valid for bools const BAD_BOOL: bool = unsafe { DummyUnion { u8: 42 }.bool}; //~^ ERROR this constant likely exhibits undefined behavior // The value is not valid for any union variant, but that's fine // unions are just a convenient way to transmute bits around const BAD_UNION: Foo = unsafe { Bar { u8: 42 }.foo }; fn main() {}